• Feature extraction
  • Reduce data content while preserving useful information
  • Common features
    • Edges
      • Resembles line drawing
    • Corners
      • Motion analysis
• Camera model
  • Considerations
    • Pose of camera
    • Perspective projection
    • CCD imaging
• Ambiguity resolution
  • Depth information lost in 3D projections onto 2D images
• Shape
  • From texture
    • Assumption
      • Homogeneous (isotropic) texture
  • From shading
    • Depends on
      • Surface orientation
      • Direction & intensity of light source
    • Assumption
      • Lambertian lighting model
      • Isotropic surface reflectance
      • Known illumination direction
• Structure
  • Stereo vision
    • Left & right images triangulated
      • Corresponding problem
  • From motion
    • Motion of features tracked as the camera moves
      • Trajectories